摘要
伊犁盆地南缘中—下侏罗统碎屑岩的物源特征,可为南天山造山带的演化提供重要证据。对其碎屑岩锆石U-Pb定年研究结果表明,伊犁盆地南缘坎乡下侏罗统八道湾组砂岩的碎屑锆石年龄集中在290~260 Ma,而下侏罗统三工河组的碎屑锆石年龄集中在350~290 Ma和460~390 Ma,中侏罗统西山窑组的碎屑锆石年龄集中在370~320 Ma和450~390 Ma。所有测试样品中前寒武纪的年龄记录非常少。这些特征表明,伊犁盆地南缘中生代碎屑沉积物主要来自于伊犁—中天山地块南部。测试样品中几乎不存在晚二叠世—中三叠世的碎屑锆石,与南天山造山带的岩浆岩记录一致,暗示在晚二叠世—中三叠世南天山地区并没有发生强烈的与碰撞或后碰撞相关的岩浆活动。该结果不支持塔里木克拉通与伊犁—中天山地块在晚二叠世—中三叠世碰撞的观点。结合高压—超高压变质岩的数据和地层记录,认为塔里木克拉通与伊犁—中天山地块的碰撞发生在晚石炭世。同时,样品中最年轻锆石的年龄数据从早侏罗世到中侏罗世逐渐增大,显示了揭顶沉积的特点。对伊犁盆地南部中生代的锆石年龄数据与同时代南天山地区的锆石年龄数据进行综合对比表明在早—中侏罗世发生构造沉积夷平的特征。
The provenance features of the middle and lower Jurassic clastic rocks in southern margin of the Yili Basincan provide important information for insights into the evolution of southern Tianshan Orogenic Belt. Detrital zircon ageof the Badaowan Formation sandstone of lower Jurassic in southern margin of the Yili Basin demonstrates a prominentage population at 290-260 Ma, whereas the Sangonghe Formation of lower Jurassic shows two prominent age popula-tions at 350-290 Ma and 460-390 Ma, respectively. The Xishanyao Formation of middle Jurassic has two prominentdetrital zircon age populations at 370-320 Ma and 450-390 Ma. All study samples have little zircon age record of Pre-cambrian period. These features indicate that Mesozoic detrital sediments in southern margin of the Yili Basin predomi-nantly might be derived from the south part of the Yili-Central Tianshan Block. The late Permian to middle Triassiczircons are nearly absent, consistenting with magmatic record in the South Tianshan Orogenic Belt and probably indi-cating no strong magmatic activities associated with collision or post-collision occurred in South Tianshan Block duringlate Permian-middle Triassic periods, which does not support the idea that the collision between the Tarim Craton andYili-CTS Block occurred in the late Permian-middle Triassic periods. Combined with previously published data of tec-tonic exhumation of high to ultrahigh pressure metamorphic rocks and stratigraphic records, these data support the ideathat the collision between the Tarim Craton and Yili-CTS Block occurred in the late Carboniferous period. The youn-gest detrital zircon ages of the studied samples are increasing from the middle-late Triassic to early Jurassic periods tomiddle Jurassic period, indicating a feature of unroofing and sedimentation. Integration of the provenance data of Mes-ozoic strata in the southern Yili Basin with the time equivalent of the South Tianshan Belt, provides an integrated re-cord of the tectonic subsidence and planation in the early-middle Jurassic period.
作者
石鑫
侯明才
黄虎
胡小龙
江文剑
吴斌
缪宗利
郑斯赫
SHI Xin;HOU MingCai;HUANG Hu;HU XiaoLong;JIANG WenJian;WU Bin;MIAO ZongLi;ZHENG SiHe(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;School of Earth Science,East China University of Technology,Nanchang 330013,China)
出处
《沉积学报》
CAS
CSCD
北大核心
2018年第3期446-455,共10页
Acta Sedimentologica Sinica
基金
国家重点基础研究发展计划(“973”计划)项目(2015CB453001)
成都理工大学沉积地质学科研创新团队(KYTD201703)
成都理工大学中青年科研骨干教师培养计划(KYGG201718)
关键词
物源
中下侏罗统
伊犁盆地南缘
南天山造山带
锆石U-PB年代学
provenance
middle-lower Jurassic
southern margin of the Yili Basin
South Tianshan Orogenic Belt
zircon U-Pb chronology